In the medical profession, a physician may wish to confirm a change in a diseased or affected part after a lapse of time. In a case in which a CT (Computed Tomography) apparatus is used to make this confirmation, for example, images of the same diseased or affected part need to be extracted from groups of CT images captured at different points in time.
The CT apparatus generates images of the body sliced from a parietal in a direction towards a toe. In a case in which a position of a desired body part does not change within the body, and a position of the image of this desired body part in a sequence of images from the parietal or the toe can be specified in the group of CT images captured at another point in time, the images at the specified position in the sequence of images can be extracted from the groups of CT images captured at different points in time, so as to obtain the images of this desired body part.
An example of the related art is described in International Publication Pamphlet No. WO2009/150882, for example.
However, the position of a tip end part (a side farther away from a bronchial tube) of a lung, or the like moves up and down, for example, depending on a movement of a diaphragm at a time of breathing, and a slice position of the image capturing the desired body part may change. For this reason, it is difficult to determine the position of the image of the desired body part in the sequence of images captured at one point in time, in the sequence of images captured at another point in time.
A technique that compares features of images may be used to search, from the group of CT images captured at the other point in time, the body part having features similar to those of the desired body part included in the group of CT images captured at the one point in time. In this case, it is necessary to detect the features from the plurality of sliced images, and to collate the sliced images captured at the different points in time in order to find a match. For this reason, it takes a long processing time to search and find the image of the body part similar to the desired body part, and the search for the image of the body part having the features similar to those of the desired body part may not be completed within a desired length of time.